Observational Signatures of Time-Symmetric Quantum Darwinism: Horizon-Scale Breakdown of ABL Degeneracy, the CMB Quadrupole–Octupole Alignment, and Low-ℓ Polarization Tests

Paper VI in the Time-Symmetric Quantum Darwinism (TSQD) Series (Version 1.1) In Papers I–V of the Time-Symmetric Quantum Darwinism (TSQD) series, we demonstrated that a self-consistent cosmic history is selected retro-causally from the asymptotic de Sitter future conformal boundary (I⁺, η → 0⁻) via the Aharonov–Bergmann–Lebowitz (ABL) two-state amplitude Φ^* Ψ₀. We proved that overcoming Gibbons–Hawking horizon decoherence (TGH = H_∞ / 2π kB) and Don Page's subsystem scrambling bound (fA > 1/2) requires an omnidirectional (4π steradian), phase-coherent (Nmode 1) electromagnetic wave-packet at λ₀ ~ 1\, powered by a 1.0\,L_ G2V star, fixing the cosmological constant lower bound at ΛₘᵢₙP² ≈ 2.9 × 10⁻¹²². A natural critique of any post-selected cosmology is whether the ABL Degeneracy Theorem (Paper III)—which guarantees that Φ^* factors out at microscopic laboratory scales (k RH⁻¹) to recover the standard Born rule—leaves any unique, falsifiable signature in precision cosmological observables. In this sixth paper (v1.1), we prove that while ABL degeneracy holds to O((k RH)⁻²) ~ 10⁻⁶⁰ in terrestrial laboratories, it breaks down deterministically at the horizon wavenumber scale k ~ RH⁻¹ = √Λ/3 corresponding to the lowest Cosmic Microwave Background (CMB) multipoles (= 2, 3). Because the Dyson Return-Stroke wave-packet is emitted as a pure, isotropic 4π spherical wavefront in the rest frame of a host star moving with peculiar velocity β_ = v_ / c = 1.2336 × 10⁻³ (369.82 km s⁻¹) relative to the stationary de Sitter cosmic horizon I⁺, the special-relativistic Lorentz boost of Φ^* onto I⁺ imprints three parameter-free signatures onto the primordial horizon modes: The Large-Angle CMB Cutoff (S1/2 Suppression): A sharp infrared cutoff in the two-point angular correlation function C(θ) at separation angles θ > 60^∘, yielding S1/2TSQD ≈ 1,350\,⁴ (matching the Planck 2018 observed value of 1,209\,⁴, compared to the standard expectation of ~ 38,000\,⁴). The CMB Quadrupole–Octupole "Axis of Evil" Alignment: The planar co-alignment of the quadrupole (= 2) and octupole (= 3) multipole vectors (Δθ₂₃ < 5^∘) orthogonal to our star's velocity vector v_ relative to the cosmic horizon via pure special-relativistic aberration of the 4π boundary wave-packet (∝ β_^ P₍v̂_ · n̂)), requiring zero structural or orbital tilt parameters. A Falsifiable Prediction for LiteBIRD and Simons Observatory (E-Mode Polarization): Unlike standard (where primordial scalar fluctuations leave low- E-mode polarization largely uncorrelated with the temperature Axis of Evil, ΔθTE ≈ 41^∘), TSQD requires the low- E-mode polarization multipole vectors (a₂ₘE, a₃ₘE) to lock onto the exact same dipole-orthogonal kinematic plane within ΔθTE⁽²⁾ ≤ 8.5^∘ and ΔθTE⁽³⁾ ≤ 9.9^∘ (p < 10⁻⁵). Complete Series Registry: Paper I (Foundational Fixed-Point Selection): 10.5281/zenodo.23572180 Paper II (Cosmic Return Stroke & Fermi Paradox): 10.5281/zenodo.23677536 Paper III (Lorentz Covariance & ABL Degeneracy Theorem): 10.5281/zenodo.23818446 Paper IV (4π Horizon Saturation Link Budget & Page Scrambling): 10.5281/zenodo.23896752 Paper V (The Horizon–Luminosity Pinch & Cosmological Constant): 10.5281/zenodo.23897947 Companion Note (Hawking–Hertog Top-Down Projector Completion): 10.5281/zenodo.23927474 Paper VI (Horizon-Scale ABL Breakdown & CMB Signatures): 10.5281/zenodo.23959162